New high-flow "cloud" catheter for safer delivery of contrast material

Study of catheter designs and drug mixing processes using 2D steady numerical simulations

The effectiveness of substance delivery through catheters is an important issue in interventional radiology, especially for infusion therapies where the pharmacokinetic advantage of local intra-arterial drug administration has been firmly established. In principle, the procedure is used to provide appropriate local concentrations while maintaining low systemic values so as to minimise the global effect and toxicity of the intervention. However, poor drug mixing may produce excessive local concentrations potentially damaging for the surrounding tissues and may lead to unsuccessful therapies. These phenomena have been observed in the infusion therapies of liver cancers through the hepatic artery and with brain tumour therapies through the carotid artery. Many aspects of the drug delivery methodology have been explored in order to determine the infusion conditions that would provide optimal mixing: the catheter tip design is considered one of the most important characteristics to be investigated for this purpose. Interestingly, it turns out that angiographic procedures could also benefit from this, because better mixing properties are associated with designs that provide potentially less harmful flow conditions such as jets, whipping and recoil of the catheter on the vascular wall. A 2D steady numerical model is proposed, to simulate the main physical processes occurring during catheter substance infusion: blood dynamics is taken into account with the Navier-Stokes equations and substance dispersion by the flowing blood with the advection-diffusion equation. The model is used to evaluate mixing properties of certain catheter designs in different flow conditions. In particular, two types of side hole catheter are compared in the context of water bath injection and in the context of vessel injection. The simulations suggest that the improved mixing reported with water bath experiments would not be maintained in the clinical context of arterial circulation.

Injection characteristics and downstream contrast material distribution of flush aortography catheters: in vitro study

Performance of 11 commercially available 4- and 5-F aortic flush catheters was evaluated with respect to the extent of upstream injection, catheter motion, and downstream homogeneity of a 10-, 15-, and 20-mL/sec bolus of 76% meglumine sodium diatrizoate at room temperature. Tests were made in a pulsatile aortic flow model containing circulating fluid isoviscous to blood. The injection process was recorded on videotape. Homogeneity of the contrast material bolus was determined spectrophotometrically from samples collected from the center and each of the four quadrants of the vessel lumen. Upstream contrast material injection between 1.5 and 7 cm in length emerged from all catheters; it was lowest with one of the "tennis racket" designs from one and a new spiral end-loop design (Halo) from another manufacturer. All catheters, except the most rigid and largest-caliber catheter (5.8 F) showed considerable shaft motion at the higher injection rates. Downstream contrast material mixing homogeneity was always best at the highest injection rate but altogether was better for the Halo catheter than for any other catheter tested. It is concluded that all tested 4- and 5-F aortic flush catheters show some undesirable features, but certain design modifications improve performance and comparative testing is helpful to distinguish such features.

Compact contrast material bolus with a new 5-F angiographic catheter

The conventional pigtail catheter was compared with the 5-F Tennis Racquet catheter for abdominal aortography with digital subtraction angiography. Resulting aortograms were judged on the basis of the quality of aortic opacification and renal artery visualization. The authors concluded that the Tennis Racquet catheter produces a more compact contrast material bolus, and its use is associated with acquisition of superior abdominal aortograms.